Biofuel production methods

ABSTRACT

In some embodiments, the present disclosure provides methods for producing biofuel from a biological material that includes protein and a biofuel feedstock, such as triglycerides. In a specific example, the biological material is hydrolyzed to obtain the biofuel feedstock, such as by treatment with a base. Free fatty acids or triglycerides are then extracted using an organic solvent. The free fatty acids or triglycerides are converted to fatty acid esters, useable as biofuel, by esterification or transesterification, respectively. In a more specific example, the biological material is converted to a biofuel in a one step process by treating the biological material with base and an appropriate alcohol. In some implementations, a disclosed method uses chicken feathers obtained from a chicken processing operation as the biological material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of, and incorporates by reference,U.S. Provisional Patent Application No. 60/884,173, filed Jan. 9, 2007,and U.S. Provisional Patent Application No. 60/970,790 filed Sep. 7,2007.

FIELD

The present disclosure describes methods of producing fuels frombiological materials. In specific examples, the present disclosureprovides methods for producing biodiesel from biological sources whichinclude protein and triglycerides, such as chicken feathers.

TECHNICAL BACKGROUND

The United States produces 2-4 billion pounds of chicken feathers frompoultry industries. Science News, “Materials Take Wing”, Feb. 23, 2002,Vol. 161. In recent years it has been shown that chicken feathers can beused for many applications, including environmental application andfiltration of heavy metals. P. Kar & M. Misra, “Use of keratin Fiber forSeparation of Heavy metals from Water”, Journal of Chemical Technology &Biotechnology, 79, 1313-1319, 2004; M. Misra & P. Kar, “Avian KeratinProtein Nano-Fiber for Environmental Application,” Natural Fibers,Plastics & Composite, 83-89, August 2000. However, much of this materialis unused, and can present disposal problems.

The availability and cost of petroleum based fuels continues to be ofconcern. A number of efforts are underway to develop fuels from othersources, such as hydrogen-based fuel sources, ethanol, and biologicalbased fuels, such as biodiesel. In particular, various plant and animaloils and fats have been investigated as potential sources of biofuel.However, the energy and resources needed to produce biofuel can make ituneconomical to produce crops specifically for biodiesel production.While waste oil and fats can be used, their supply may be insufficientfor mass production of biofuel.

SUMMARY

The present disclosure provides methods for producing fuels, such asbiofuels, from biological materials. In a particular disclosed method,biofuel is produced by hydrolysis of the biological material to liberatetriglycerides, free fatty acids, or other substances which can beconverted to fatty acid esters useable as biofuels. In a particularimplementation, the biological material includes a protein, which ishydrolyzed using an alkaline solution in some examples. The free fattyacids or triglycerides are then esterified or transesterified,respectively, to produce fatty acid esters useable as biofuel. Forexample, when triglycerides are obtained from the biological material,the triglycerides can be transesterified by treating them with astrongly alkaline solution, although other methods are used in furtherexamples. When free fatty acids are obtained, the free fatty acids maybe esterified using an acid catalyzed reaction. In a more particularimplementation, triglycerides in the biological source are converted tofatty acid esters in a one step process using basic conditions and analcohol, or derivative thereof, bearing the appropriate functionalgroup.

In a specific embodiment, a protein source is hydrolyzed using a base.Free fatty acids or triglycerides are then extracted using an organicsolvent. Extracted free fatty acids are then esterified, such as usingacid catalyzed esterification and the appropriate alcohol. Extractedtriglycerides are then transesterified, such as using a base catalyzedprocess.

In a further embodiment, the free fatty acids are converted toglycerides, such as mono-, di-, or tri-glycerides by reaction withglycerol under appropriate conditions. The gylcerides are thentransesterified to produce fatty acid esters, which may be used asbiofuels. In a specific example, the glycerides are transesterifiedusing a base catalyzed reaction.

The biological source may be any suitable biological material havingprotein, such as a structural protein, such as keratin, andtriglycerides or fatty acids. In various examples the biological sourceis hair, feathers, skin, hooves, claws, horns, or scales. In a specificexample, the protein source is feathers, such as poultry feathers. Insome examples, the feathers are obtained from a poultry processingoperation.

In some aspects of the present disclosure, the biological source, orfree fatty acids or triglycerides obtained therefrom, is combined withanother feedstock, such as a plant oil, such as a vegetable oil,including soybean oil or rapeseed oil, coffee oil, or an animal fat,such as chicken fat. The combined feedstock is then converted to abiofuel, such as using an above-described hydrolysis and/oresterification or transesterification procedure. In further aspects, abiofuel produced from the above-described biological material iscombined with a biofuel derived from a different feedstock, such as aplant oil, such as a vegetable oil, including soybean oil or rapeseedoil, oil from coffee, or from an animal fat, such as chicken fat.

The methods of the present disclosure can provide a number ofadvantages. For example, the present disclosure can convert chickenfeathers, often treated as a waste product, into a high value biofuelproduct. Accordingly, the supply of biofuel can be increased without theexpenditure of energy and other resources in developing a feedstockspecifically for use as a biofuel.

There are additional features and advantages of the subject matterdescribed herein that will become apparent as this specificationproceeds.

In this regard, it is to be understood that this is a brief summary ofseveral aspects of the subject matter described herein. The variousfeatures described in this section and below for various embodiments maybe used in combination or separately. Any particular embodiment need notprovide all features noted above, nor solve any particular set ofproblems in the prior art noted above.

DESCRIPTION OF THE FIGURES

Various embodiments are shown and described in connection with thefollowing drawings in which:

FIG. 1 is a schematic diagram of various methods of extracting a biofuelfeedstock, such as free fatty acids or triglycerides, from chickenfeathers.

FIG. 2 is a schematic diagram of various methods of convertingtriglycerides and free fatty acids to fatty acid esters.

FIG. 3 is a process diagram of a disclosed method of synthesizingbiodiesel from chicken feathers.

FIG. 4 an HPLC chromatogram of a product produced using the method ofFIG. 3.

FIG. 5 is an HPLC chromatogram of a biodiesel product produced using amethod of the present disclosure.

FIG. 6 is an FTIR spectra of the biodiesel product of FIG. 5.

FIG. 7 is a GC-MS spectra of the biodiesel product of FIG. 5.

FIG. 8 is a photograph of a biodiesel sample obtained from chickenfeathers using a method of the present disclosure.

DETAILED DESCRIPTION

Unless otherwise explained, all technical and scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which this disclosure belongs. In case of conflict,the present specification, including explanations of terms, willcontrol. The singular terms “a,” “an,” and “the” include pluralreferents unless context clearly indicates otherwise. Similarly, theword “or” is intended to include “and” unless the context clearlyindicates otherwise. The term “comprising” means “including;” hence,“comprising A or B” means including A or B, as well as A and B together.

Although methods and materials similar or equivalent to those describedherein can be used in the practice or testing of the present disclosure,suitable methods and materials are described herein. The disclosedmaterials, methods, and examples are illustrative only and not intendedto be limiting.

The present disclosure generally provides methods of producing biofuelsfrom biological materials. Typically, the biological material includestriglycerides or fatty acids and a protein, such as a structuralprotein. In a specific example, the structural protein is keratin.Suitable biological sources include hair, feathers, skin, hooves, claws,horns, or scales. In a specific example, the protein source is feathers,such as poultry feathers. In some examples, the feathers are obtainedfrom a poultry processing operation. In a more specific example, thebiological source is chicken feathers.

Chicken feathers typically constitute about 18 wt % of the mass of achicken. The feathers themselves contain about 84 wt % protein, about 12wt % triglycerides, and about 4 wt % ash, phosphorous and trace metals.The triglycerides in the chicken feathers can be converted to biodieselusing the disclosed methods. Although the following methods specificallydescribe the use of chicken feathers, similar methods may be used forother, similar, biological sources.

As shown in FIG. 1, chicken feathers 110 can be converted totriglycerides 120 or fatty acids 125 through a variety of pathways. Thechicken feathers 110 can be obtained from a variety of sources, such aspoultry processing operations. In some embodiments the feedstock ispretreated to aid the subsequent conversion reactions. For example,chicken feathers may be first crushed or ground, such as by cryogenicgrinding or grinding in a burr grinder, conical burr grinder, bladegrinder, or hammer mill. The feedstock may also be pretreated byvibration. The chicken feathers may also be subjected to one or morecleaning steps.

One conversion pathway 130 is base hydrolysis. Base hydrolysis istypically carried out by refluxing a quantity of chicken feathers with aconcentrated aqueous solution of base, such as an alkaline earth oralkali metal hydroxide. Other inorganic or organic bases may also beused. In particular examples, the basic solution is a NH₄OH, KOH or NaOHsolution, such as a solution having a concentration of between about 2Mand about 8M, such as about 4M. The hydrolysis process is typicallycarried out from about 1 hour to about 8 hours, such as about 4 hours.The chicken feathers typically dissolve in the basic solution as thereaction proceeds. After the reaction has reached a desired level ofcompletion, the reaction mixture is neutralized, such as by adding anacid, such as an about 1M hydrochloric acid solution to about a 12Mhydrochloric acid solution, such as a 6M hydrochloric acid solution.Other mineral acids or organic acids can be used, if desired, for theneutralization.

The triglycerides in the feathers are typically converted to fatty acidsduring base hydrolysis. After neutralization, a solid precipitatetypically forms. Fatty acids and other components are extracted from theneutralized reaction mixture, typically using one or more organicsolvents. Typical solvents include alcohols, such as methanol, ethanol,and isopropanol; hydrocarbons, such as paraffinic hydrocarbons having4-8 carbons, such as hexane and petroleum ether; chlorinated solvents,such as dichloromethane and chloroform; ethers, such as diethyl ether;aldehydes and ketones, such as methyl ethyl ketone and acetone;fluorinated compounds; and mixtures thereof. In a specific example, a 5%by volume solution of methanol in dichloromethane is used for theextraction.

In some methods, the solvent is selected to extract selected componentsof interest. For example, relatively nonpolar solvents may be used toextract fatty acids, yet avoid extraction of water and other materials.Fatty acids thus obtained may require fewer processing steps.

Extraction can occur in a batch or continuous process. Suitablecontinuous processes include countercurrent extraction processes. Insome examples, the reaction mixture is refluxed with solvent for aperiod of time, such as between about 30 minutes and about 24 hours,such as between about 1 hour and about 8 hours. In a particular example,the mixture is refluxed for about 1 hour.

After solvent extraction, the solvent may be removed prior to furtherprocessing of the fatty acids. Solvent removal may be accomplished byany suitable method, many of which are notoriously well known in theart. For example, the solvent may be distilled from the desired product.In particular implementations, solvent removal occurs under reducedpressure, such as under a full or partial vacuum, in order to reduce thetemperature at which the solvent distills, and thus the heat energyneeded to volatilize the solvent. In more particular implementations,rotary evaporators or similar devices are used to remove solvent. Whenmixed solvent systems are used, fractional distillation can be performedand suitable distillation columns incorporated into the solvent removalprocess or apparatus in order to aid separation of the different solventcomponents. Fractional distillation can also be used to purify the freefatty acids or to separate the fatty acids from other components. Ofcourse, if mixed recovery of solvents is not of concern, fractionaldistillation need not be performed.

Solvent obtained from the above-described solvent removal in process canbe recycled into other parts of the system, such as into the solventextraction process. Appropriate choice of solvents and operatingconditions can result in substantial reuse of the solvent, decreasingmaterials costs and potentially environmentally harmful waste products.In some embodiments, over 85% of the solvent used in the extraction stepis recovered, such as over 95%. The free fatty acids can then beesterified, such as using the processes discussed below.

Acid hydrolysis 135 can be carried out in a manner similar to basehydrolysis. Typically, the material is refluxed (such as at about 110°C.) in HCl, such as about 6M HCl, for about 4 to about 24 hours.Neutralization may be carried out with a suitable base, such as sodiumhydroxide, potassium hydroxide, or other organic or inorganic bases,including alkaline earth or alkali metal oxides or hydroxides. Thetriglycerides thus obtained can be extracted or purified as describedabove for the free fatty acids produced during basic hydrolysis.

Another method 140 of isolating triglycerides from chicken feathersinvolves refluxing the chicken feathers in N,N,-dimethyl formamide foran extended period of time and then separating the triglycerides usingfiltration. One procedure for carrying out this process is disclosed inU.S. Pat. No. 3,970,614, incorporated by reference herein.

A method 150 involves extracting triglycerides from chicken feathersusing water at high temperature and pressure. Suitable techniques aredescribed in Yin et al., “Self-organization of Oligopeptides Obtained onDissolution of Feather Keratins in Superheated Water,”Biomacromolecules, 8 800-806 (2007), incorporated by reference herein.For example, chicken feathers can be hydrolyzed using superheated orsupercritical water.

In a specific example, the chicken feathers are placed in a suitablepressure vessel, such as a stainless steel vessel, and heated until thepressure cell reaches a temperature of about 220° C. and a pressure ofabout 22 bar. The feathers are held in this state until a desired degreeof hydrolysis has occurred, such as about 2 hours. The triglycerides canbe separated from other components, such as proteins and amino acids,using suitable techniques, such as extraction or gravity separation,such as using a hydrocyclone or a separatory funnel. Additional detailregarding procedures for dissolving polymers, including biologicalpolymers such as keratin, using this type of methodology can be found inRastogi et al., “Dissolution of Hydrogen-Bonded Polymers in Water: AStudy of Nylon-4,6,” Macromolecules 37, 8825-8828 (2004), expresslyincorporated by reference herein in its entirety.

Path 170 illustrates yet another method of obtaining triglycerides fromchicken feathers. Chicken feathers are treated with urea and2-mercaptoethanol, as described in Schrooyen et al., “PartiallyCarboxymethylated Feather Keratins. 2. Thermal and Mechanical Propertiesof Films,” J. Agric. Good Chem. 49, 221-230 (2001), incorporated byreference herein. After solubilization, excess reagents can be removedthrough suitable means, such as dialysis.

A one step procedure 180 can be used to extract triglycerides andconvert them to fatty acid esters. For example, the chicken feathers maybe refluxed with an alcohol bearing the desired functional group, suchas methanol, and an esterification regent or catalyst, such as sodiumhydroxide, ammonium hydroxide, or sodium methoxide. Although otheresterification reagents or catalysts can be used, methoxide-basedtransesterification procedures can help reduce the nitrogen and sulfurcontent of the resulting biofuel.

The triglycerides 120 can be subjected to further processing steps priorto transesterification. For example, the triglycerides 120 can be washedto remove free fatty acids and other materials. In some embodiments, thewash is carried out with an alcohol, such as methanol or ethanol, oracetic acid. Multiple washings can increase the amount of free fattyacid removed, thus increasing the pH towards neutral. In someembodiments, the triglycerides 120 are washed until the pH issufficiently neutral, such as to a pH of at least about 6.7.Particularly when water sensitive materials are used in the subsequenttransesterification step, the triglycerides 120 can be dried, such asusing molecular sieves or similar materials, such as zeolites, silicagels, or acidic clays, or other drying agents, such as sodium sulfate,calcium chloride, magnesium sulfate, potassium carbonate, and calciumsulfate. If needed or desired, the pH of the triglycerides 120 can beadjusted, such as to a neutral pH, using standard methods, such asaddition of an acid or base. The triglycerides 120 can be furtherpurified or fractionated, such as using distillation, as described inU.S. Pat. No. 3,704,132, incorporated by reference herein.

After solvent removal or any other desired processing steps, thetriglycerides 120 are converted to esters, useable as biofuel, in atransesterification process. Any suitable transesterification processmay be used in the methods of the present disclosure, many of which arenotoriously well known in the art. For example, a number of acid andbase catalysts are disclosed in U.S. Pat. No. 5,424,420 and inSchuchardt et al., J. Braz. Chem. Soc., 9(1), 199-210 (1998), each ofwhich is incorporated by reference herein. FIG. 2 illustrates a numberof methods for converting triglycerides 210 and fatty acids 215 to fattyacid esters 220.

The hydrolysis processes described above, as well as the esterificationand transesterification processes described below, can be carried out inthe presence of mechanical mixing or ultrasonic treatment. Suchtreatment can, for example, aid in mixing the fatty acid or triglyceridewith the alcohol, catalyst, other reagent or solvent, as triglyceridesmay be immiscible, or have limited miscibility, in the alcohol.Agitation may be accomplished by a paddle or blade stirrer attached to amotor, such as a motor operating at about 100 rpm to about 1000 rpm,such as about 300 rpm to about 700 rpm or about 400 rpm to about 600rpm. Stirring may be accomplished by other means, such as using amagnetic stirring device, or other means of agitation used, such as ashaker.

In further embodiments, ultrasonication, optionally in combination withagitation, is applied during all or a portion of a hydrolysis,esterification, or transesterification process. Suitable ultrasonicationdevices are available from Hielscher Ultrasonics GmbH of Teltow, Germanyand Branson Ultrasonics Corporation of Danbury, Conn. Ultrasonicators ofany suitable power can be used, such as those having a frequency of16-45 kHz, power 100-500 W, 20-400 mW/cm². Ultrasonication power andduration can be selected based on various factors, including the alcoholused for transesterification, the nature of the catalyst, the reactiontemperature, and the process conditions of the reaction, such as whetherthe transesterification occurs as a batch or continuous process. Forexample, the reaction size or reactant flow rate may influence the poweror duration of ultrasonication used.

Ultrasonication may have other benefits, such as reducing the reactiontime and reducing the amount of catalyst or alcohol used in theesterification or transesterification. In some examples, ultrasonicationis carried out while the reactants are under pressure, such as a gaugepressure of about 1 bar to about 3 bar.

The hydrolysis, esterification, and transesterification reactions may becarried out under any suitable conditions. In some methods the reactionsare carried out at room temperature or higher, optionally in apressurized vehicle, such as an autoclave. The use of highertemperatures and pressures may aid in solubilizing the components of thefeedstock.

In typical esterification or transesterification reactions, an alcoholcontaining the desired substituent group is added to the free fatty acidor triglyceride. Such alcohols can be represented by R—OH, where R isthe desired ester group, typically a short chain hydrocarbon, such as aC₁-C₄ hydrocarbon, which may be linear or branched. In more particularexamples, the alcohol is methanol or ethanol. Alcohol is typicallymaintained in a stoichiometric excess, such as at a ratio of alcohol totriglyceride or free fatty acid of between about 3:1 and about 40:1,such as about 6:1 to about 12:1 or between about 9:1 and about 12:1. Ina specific example, the ratio of alcohol to triglyceride or free fattyacid is about 9:1. In further examples, the transesterification oresterification mixture includes from about 20% to about 60% alcohol byvolume.

In some embodiments, the transesterification is carried out in thepresence of a cosolvent. A cosolvent may, for example, aid in mixing ofthe alcohol and triglyceride, which can enhance the reaction rate.Suitable cosolvents include pyridine, tetrahydrofuran, hexane,bis-(dimethylsilyl)trifluoroacetamide, and methyl tert-butyl ether.

With continuing reference to FIG. 2, in at least certain methods,transesterification is accomplished using acid 230 or base 240catalysis, each of which is further described below. Base catalyzedtransesterification 240 is typically better for relatively cleantriglyceride sources, such as those which lack substantial amounts offree fatty acids and are relatively water-free. Base catalyzedtransesterification is typically faster, more complete, and produces ahigher purity product compared with acid catalyzed transesterification.However, acid catalysis 230 can be useful when the starting material isnot well suited for the base catalyzed process 240.

Transesterification process 230 is catalyzed using a catalytic amount ofacid, which may be an organic acid, a mineral acid, or a Lewis acid.Suitable acids include aluminum chloride, benzyl sulfonic acid, borontrifluoride, dichloroacetic acid, hydrochloric acid, iodic acid,methanesulfonic acid, phosphoric acid, nitric acid, acetic acid, citricacid, malic acid, adipic acid, tartaric acid, fumaric acid, p-toluenesulfonic acid, stannic chloride, sulfonic acid, sulfuric acid, andtrichloroacetic acid. In at least some examples, the acid or acids usedto catalyze the transesterification have an acid dissociation constant(pK_(a)) of about 2 or less, such as about 1 or less.

Transesterification process 240 is carried out using a base catalyzedmethod, such as using organic bases, Lewis bases, or inorganic bases.Suitable base catalysts include alkali metal hydroxides, such as sodiumhydroxide and potassium hydroxide, and alkaline earth metal oxides andhydroxides, such as magnesium oxide, calcium hydroxide, calcium oxide,barium hydroxide, and strontium hydroxide.

Transesterification also may be accomplished using a combination of base240 and acid 230 catalysis. For example, a portion of the triglyceridesmay be transesterified using an acid catalyst and then a basic catalystadded to the reaction mixture. The basic catalyst is typically added inan amount sufficient to act as a catalyst for the transesterificationand an additional amount to neutralize the acid catalyst. Salts formedfrom the acid-base reaction can be removed following thetransesterification, such as by washing the fatty acid ester with water.Suitable techniques for such acid/base catalyzed transesterification aredescribed in U.S. Patent Publication US 2006/0094890, incorporated byreference herein.

A further transesterification method 250 involves treating thetriglyceride with an alkoxide of a hydrocarbon alcohol having thedesired ester group, such as methoxides or ethoxides. Methoxides aretypically prepared from alkali metals, such as sodium and potassium. Inparticular examples, the transesterification is carried out using sodiummethoxide. Alkoxides typically react with water and thus, in someimplementations, the transesterification process 250 uses water-free orsubstantially water-free materials. Molecular sieves or similarmaterials, such as zeolites, silica gels, or acidic clays, or otherdrying agents, such as sodium sulfate, calcium chloride, magnesiumsulfate, potassium carbonate, and calcium sulfate, may be included inthe reaction vessel in order to help remove water from the reactionenvironment.

The transesterification reaction is carried out for a time sufficient toallow the reaction to reach a desired level of completion. The reactiontime may vary based on the reactants (such as the catalyst and alcoholused) and the reaction conditions, including the temperature of thereaction and the nature of the reaction vessel. Typically, reaction iscarried out for a period of about 1 minute to about 72 hours, such asbetween about 5 minutes and about 2 hours or between about 5 minutes andabout 15 minutes. Reaction temperature is typically between about 10° C.and about 200° C., such as between about 25° C. and about 75° C. Thereaction temperature may depend on the alcohol used, the reaction time,and other process conditions. For example, acid catalyzedtransesterification can take substantially longer than base catalyzedmethods, and are typically carried out at higher temperatures.

When the transesterification is catalyzed, a stoichiometric amount ofcatalyst is not needed. In particular examples, the amount of catalystis from about 1 wt % to about 40 wt % based on the amount oftriglyceride to be transesterified, such as between about 1 wt % andabout 10 wt % or between about 1 wt % and about 2.5 wt %. Fornon-catalytic transesterifications, the amount of transesterification istypically included in at least a stoichiometric amount, and is added instoichiometric excess in more particular examples.

In some implementations, excess catalyst is used to neutralize freefatty acids or other materials in the triglyceride. The presence of freefatty acids is determined, in some embodiments, by measuring the pH ofthe triglyceride. Acidic pH, such as less than about 6.7, can indicatethe presence of free fatty acid. Catalyst, or other base, can be added,when base catalyzed transesterification is used, to neutralize the freefatty acid, such as adding base until the pH of the triglyceride issufficiently neutral.

In further examples, other transesterification processes are used inplace of or in addition to those discussed above. For example,transesterification can be carried out by enzymatic processes 260. Inaddition, transesterification can be carried out using supercriticalmethanol 270, such as at about 350° C. and about 35 Mpa. Supercriticalmethanol transesterification is typically complete in a relatively shorttime, such as about 4 minutes. Transesterification using supercriticalmethanol can be advantageous as it does not typically require acid orbase and can thus simplify subsequent purification or processing steps.Suitable techniques for enzymatic processes 260 and supercriticalmethanol processes 270 are described in Marchetti et al., “PossibleMethods for Biodiesel Production,” Renewable and Sustainable EnergyReviews 11 1300-1311 (2007) and references cited therein, each of whichis incorporated by reference herein.

When free fatty acids 215 are used to produce biofuel, Fischeresterification 280 using an acid catalyst and an appropriate alcohol istypically employed. For example, the free fatty acids 215 may berefluxed in methanol with a catalytic amount of acid, which is typicallya mineral acid such as HCl or H₂SO₄, although other acid catalysts maybe used. The reaction is allowed to proceed until a desired degree ofesterification has been reached, such as between about 5 minutes andabout 24 hours, such as about 8 hours. Molecular sieves or similarmaterials, such as zeolites, silica gels, or acidic clays, or otherdrying agents, such as sodium sulfate, calcium chloride, magnesiumsulfate, potassium carbonate, and calcium sulfate, may be included inthe reaction vessel in order to help remove water from the reactionenvironment and help drive the reaction to completion.

In some cases, it may be desirable to convert free fatty acids toglycerides, such as mono-, di-, or tri-glycerides before converting thefeedstock to fatty acid esters. This can be accomplished usingglycerolysis step 290. Glycerolysis can be performed according to anysuitable method. Suitable enzymatic methods are described in Fadilogluet al., “Reduction of Free Fatty Acid Content of Olive-Pomace Oil byEnzymatic Glycerolysis,” Food Science and Technology International 9(1)11-15 (2003) and Damstrup et al., “Process Development of ContinuousGlycerolysis in an Immobilized Enzyme-Packed Reactor for IndustrialMonoacylglycerol Production,” Journal of Agricultural and Food ChemistryA-G (Aug. 23, 2007), each of which is incorporated by reference herein.Glycerolysis may also be accomplished by adding glycerol to the freefatty acids and heating the mixture to a relatively high temperature,such as above about 200° C., such as about 250° C. to about 260° C.Addition of a suitable catalyst, such as zinc powder or zinc chloride,can decrease the needed temperature or reaction time. Once the freefatty acids have been converted to glycerides, the glycerides may betransesterified using the techniques shown in FIG. 2 and describedabove.

Although adding additional steps to the biofuel production process,glycerolysis of the free fatty acids can provide a number of advantages.For example, base catalyzed, or other non-acidic transesterificationprocesses can be easier to implement on an industrial scale, as they canbe less prone to corrode process equipment. In addition, oncetriglycerides are formed from the free fatty acids, the chicken feathertriglycerides can be combined with other feedstocks in atransesterification process. Another potential advantage oftransesterification is that yields from transesterification processes,such as base catalyzed transesterification, can be higher than Fisheresterification of free fatty acids.

After the transesterification or esterification reaction has reached adesired level of completion, the fatty acid ester product is separatedfrom reactants and reaction byproducts in a separation process. In someimplementations, the products can be neutralized, such as by an acidicwash when a basic catalyst is used in the transesterification or a basicwash when acid catalyst is used. Washing with water, such as hot water,can also be used to remove undesired materials, such as acid, from thereaction products.

Upon standing, such as for about 12, about 24, about 36, about 48, orabout 72 hours, or more, one or more layers may form, such as a fattyacid ester layer, a layer which includes soaps, such as glycerin, and alayer that includes other components, such as water, salts, andunreacted alcohol. Various processes may be used to remove the desiredlayer or layers, such as decantation, draining at the appropriate level,or sequential removal of layers.

Depending on the processes and materials used in the esterification ortransesterification, separation of the layers may be difficult or takelonger than desired. Therefore, in some examples, gravity separationdevices are used to aid in separating components of the reactionproducts. The term gravity separator, as used herein, refers to deviceswhich separate materials based on density (specific gravity). Suitablegravity separation devices include separatory funnels, hydrocyclones,and centrifuges. Ultrasonication can also aid in layer separation.

In further embodiments, the fatty acid ester product is extracted withan organic solvent, which in some embodiments is selected as describedabove for extraction of triglycerides. In particular examples, thesolvent is diethyl ether or hexane. Solvent extraction may take placeafter other steps, such as neutralization, as described above. Solventextraction of the fatty acid ester may produce a more pure product.

Glycerin formed from the transesterification process, and isolatedduring the separation process, can be further isolated, purified, andput to other beneficial uses. For example, glycerin is used in foods,plastics, lacquers, pharmaceuticals, toothpastes, tobacco, resins,cosmetics, cellulose processing, and explosives.

After separation, the fatty acid ester can be further purified ortreated. For example, the fatty acid ester can be neutralized,particularly if neutralization was not carried out during the separationprocess. When transesterification is carried out using a base oralkoxide, neutralization is typically carried out by washing the fattyacid ester product with one or more dilute acids, such as an aqueoussolution of a dilute acid. Suitable acids include organic, inorganic,and Lewis acids, such as tannic acid, citric acid, salicylic acid, malicacid, maleic acid, acetic acid, salicylic acid, and hydrochloric acid.In a particular example, a neutralization solution is used in an amountof between about 20 vol % to about 40 vol % by volume of the amount ofraw triglyceride material used in the transesterification reaction. Acidis added to this neutralization solution, in some embodiments, having aconcentration of about 0.1 mM to about a 1 M, such as between about 0.5mM to about 50 mM.

Correspondingly, a basic wash can be used to neutralize the product ofan acid catalyzed transesterification or esterification. Mineral,organic, or other suitable bases, such as Lewis bases, can be used forthe neutralization, such as alkaline and alkaline earth metalhydroxides, such as sodium hydroxide or potassium hydroxide.

Additional purification steps can be performed on the crude fatty acidester in order to make it more suitable as a biofuel. For example, thefatty acid ester can be treated with activated carbon or othersubstances to remove impurities from the product. Additional waterwashes can be performed on the fatty acid ester, such as to removeresidual salts, catalyst, alcohol, or soaps. The fatty acid esterproduct can also be dried, such as using molecular sieves or similarmaterials, such as zeolites, silica gels, or acidic clays, or otherdrying agents, such as sodium sulfate, calcium chloride, magnesiumsulfate, potassium carbonate, and calcium sulfate. The product can alsobe fractionated to remove impurities or isolate different fuelfractions.

In particular methods, the biofuel resulting from the disclosed methodsconforms to the Avian Biodiesel (ABD-06) standard. According to someaspects of the present disclosure, biofuels produced according to thedisclosed methods are mixed with other fuels, including biofuelsobtained from other sources. For example, the disclosed fuels may bemixed with biofuels obtained from plant oils, including vegetable oils,such as soybean oil or rapeseed oil, oil from coffee beans, or fromanimal fats (including chicken fat).

In yet further embodiments, the feedstock, such as chicken feathers, ismixed with another biofuel feedstock, such as plant oils, such asvegetable oils, including soybean oil or rapeseed oil, coffee beans, oranimal fat, and the combined feedstock is converted to biofuel. In someimplementations the combined feedstock is treated with alkali and theresulting product transesterified to produce a biofuel. In at least someimplementations, the use of such a combined feedstock can enhancebiofuel production or increase the quality (or otherwise adjust theproperties of) the resulting biofuel.

In order to enhance the stability or firing properties of the resultingbiofuel, various additives can be added to the biofuel producedaccording to the disclosed methods. For example, antioxidants or otherstabilizers can be added to the biofuel. Suitable antioxidants andstabilizers include 2,6-di-tert-butyl-4-methylphenol, BIOSINEOX(available from Antioxidants Aromas and Fine Chemicals (Pty) Ltd. ofRichards Bay, South Africa), tocopherols, pyrogallol, propylgallate,tert-Butylhydroquinone, and ETHANOX (available from AlbemarleCorporation of Pasadena, Tex.).

EXAMPLES Example 1

In the present Example, chicken feathers were crushed in a vibrated millto produce fine size fibrous materials. The fibrous material wasconditioned with NaOH for an extended time at room temperature. Thehydrolyzed product was mixed with freshly prepared methoxide (methanolplus NaOH). The mixed product was conditioned for 24 hours. A schematicof the process is shown in FIG. 3.

Two layers formed after the 24 hour conditioning period. The topfraction was a clear biofuel material corresponding to esterifiedproducts. The lower thick layer included glycerin and other substances.The top layer was analyzed using High Pressure Liquid Chromatography(HPLC) to determine the quality of biofuel fraction. The resultingchromatogram, shown in FIG. 4, illustrates that the biodiesel was ofgood quality.

Example 2

In this Example, chicken feathers were mixed in a pressurized autoclavein the presence of water and NaOH. The mixed product was heated at60-70° C. (external temperature 200-300° C.) for 20-30 minutes. Afterthat time, the hydrolyzed and dissolved product was mixed with sodiummethoxide (methanol and NaOH) for several hours at 60-70° C. The mixturewas then cooled to room temperature. A good and high quality biofuel(esterified product) was noticed. The presence of biofuel was confirmedby HPLC.

Example 3

In this Example chicken feathers were mixed with methanol to whichsodium hydroxide was added. The mixture was conditioned for severalhours. After conditioning, sodium methoxide was added. The resultingmixture was mixed for a long time at 25-60° C. The product was thencooled to room temperature. A clean biofuel layer (esterified product)and glycerin layer were observed. The biofuel layer was analyzed byHPLC, confirming the formation of a high quality biofuel oil.

Example 4

In this Example, chicken feathers were mixed with alkaline media,consisting of sodium hydroxide and water. The mixture was ultrasonicallytreated. The hydroxide product was then treated with freshly preparedsodium methoxide for a long time at a temperature of 25-70° C. Aftercooling, a biofuel layer was obtained. The oil layer was washed severaltimes. The oil was determined to be of high quality.

Example 5

In this Example, chicken feathers were mixed with ammonium hydroxide.The mixture was allowed to stand for an extended time. The hydrolyzedproduct was then mixed with freshly prepared ammonium methoxide for anextended period of time. The mixture was then allowed to settle forabout 24 hours. Water was added to help settle the layers.

Three different layers were observed. The upper layer was oilcorresponding to esterified products. The middle layer contained waterplus oil. The lower layer contained glycerin and other products. HPLCanalysis confirmed that the top oil layer consisted of high quality oil.

Example 6

In this Example, chicken feathers were mixed with water and sodiumhydroxide. The mixture was refluxed for 2-24 hours. The hydrolysisproduct was neutralized with hydrochloric acid. Some of the free sulfurgroups in cysteines were converted into hydrogen sulfide, which evolvedduring the neutralization process. Fatty acids were extracted with ether(dichloromethane, chloroform or a 5% solution of methanol indichloromethane can also be used for extraction). Three different layerswere observed. The upper layer was ether containing fatty acids, themiddle layer was polypeptides, and the lower layer was water containingfree amino acids. The fatty acids were collected from the top layer(ether) by evaporating the solvent under vacuum. Fatty acids wererefluxed with methanol in presence of an acid (e.g. HCl, H₂SO₄, etc.).The quality of the biodiesel produced was measured using HPLC, theresults of which are shown in FIG. 5. The product was also analyzed byFTIR, which, as shown in FIG. 6, indicates the presence of the estergroup and the hydrocarbon chains. The composition of the methyl estersof fatty acids was analyzed by GC-MS. Retention times and correspondingesters structure are shown in FIG. 7.

Example 7

In this Example, chicken feathers were hydrolyzed by refluxing withhydrochloric acid for 6 hours. Fatty acids were extracted using ether(dichloromethane, chloroform or 5% solution of methanol indichloromethane can also be used for extraction). Three different layerswere observed. The upper layer was ether containing fatty acids, themiddle layer was polypeptides, and the lower layer was water containingfree amino acids and glycerin. Fatty acids were obtained from layer oneby evaporating the solvent under vacuum. Fatty acids were then refluxedwith methanol in the presence of concentrated sulfuric acid (acidcatalyzed esterification) to produce biodiesel.

Example 8

In this Example, chicken feathers were hydrolyzed by refluxing withmethanol and sodium hydroxide for 2-12 hours. Methanol was evaporatedand fatty acids were extracted with diethyl ether (dichloromethane,chloroform or 5% solution of methanol in dichloromethane can also beused for extraction). Fatty acids were then refluxed with methanol inthe presence of concentrated sulfuric acid (acid catalyzedesterification) to produce biodiesel. A photograph of the biodiesel inmethanol obtained from chicken feathers is shown in FIG. 8.

It is to be understood that the above discussion provides a detaileddescription of various embodiments. The above descriptions will enablethose skilled in the art to make many departures from the particularexamples described above to provide apparatuses constructed inaccordance with the present disclosure. The embodiments areillustrative, and not intended to limit the scope of the presentdisclosure. The scope of the present disclosure is rather to bedetermined by the scope of the claims as issued and equivalents thereto.

1. A method of producing biofuel comprising: obtaining a biologicalmaterial, the biological material comprising protein and triglycerides;hydrolyzing the biological material to obtain free amino acids and abiofuel feedstock; and converting the biofuel feedstock to fatty acidesters.
 2. The method of claim 1, wherein the biological materialcomprises feathers.
 3. The method of claim 1, wherein the biologicalmaterial comprises poultry feathers.
 4. The method of claim 1, whereinthe biological material comprises chicken feathers.
 5. The method ofclaim 1, wherein the biological material comprises feathers obtainedfrom a poultry processing operation.
 6. The method of claim 1, whereinhydrolyzing the biological material comprises treating the biologicalmaterial with a base.
 7. The method of claim 1, further comprisingextracting the biofuel feedstock from the hydrolyzed material using anorganic solvent.
 8. The method of claim 7, wherein the organic solventcomprises at least one of diethyl ether, dichloromethane, and methanol.9. The method of claim 7, wherein the biofuel feedstock comprisestriglycerides and converting the biofuel feedstock to fatty acid esterscomprises a base catalyzed transesterification.
 10. The method of claim7, wherein the biofuel feedstock comprises triglycerides and convertingthe biofuel feedstock to fatty acid esters comprises an acid catalyzedtransesterification.
 11. The method of claim 7, wherein the biofuelfeedstock comprises triglycerides and converting the biofuel feedstockto fatty acid esters comprises treating the triglycerides with amethoxide.
 12. The method of claim 1, wherein the biofuel feedstockcomprises at least one of free fatty acids and triglycerides.
 13. Themethod of claim 1, wherein the biofuel feedstock comprises free fattyacids and converting the biofuel to fatty acid esters comprises an acidcatalyzed esterification.
 14. The method of claim 1, wherein the biofuelfeedstock comprises free fatty acids, further comprising converting thefree fatty acids to glycerides and wherein converting the biofuelfeedstock to fatty acid esters comprises transesterifying theglycerides.
 15. The method of claim 1, further comprising adding thefatty acid esters to a biofuel derived from another source.
 16. Themethod of claim 1, further comprising adding a stabilizer to the fattyacid esters.
 17. The method of claim 16, wherein the stabilizercomprises an antioxidant.
 18. A biofuel produced from the fatty acidesters of claim
 1. 19. A method of producing biofuel comprising:obtaining chicken feathers produced from a chicken processing operation;comminuting the chicken feathers; hydrolyzing the chicken feathers toobtain triglycerides; transesterifying the triglycerides to obtain abiofuel; and extracting the triglycerides or the biofuel with an organicsolvent.
 20. The method of claim 19, further comprising blending thebiofuel with another fuel.